Ferrite material

ABSTRACT

FERRIC OXIDE 38-48 LEAD OXIDE 0.5-3.0 COBALT OXIDE 0.7-2.0 NICKEL OXIDE 50.0-60.8   ARTICLES ARE MADE FROM THE HEREIN DISCLOSED NICKEL FERRITE INCLUDING COBALT OXIDE AND LEAD OXIDE ADDITIVES IN ACCORDANCE WITH THE KNOWN CERAMIC INDUSTRY TECHNOLOGY. FERRITE MATERIALS HAVING FOR THEIR BASIC COMPONENTS FERRIC OXIDE AND NICKEL OXIDE. THE FERRITE MATERIAL (FERRITE) ALSO INCLUDES COBALT OXIDE AND LEAD OXIDE, WHICH MAKES IT POSSIBLE TO EXTEND THE OPERATIONAL FREQUENCY RANGE OF THE MATERIAL UP TO 400M C.P.S. THE FERRITE HAS THE FOLLOWING COMPOSITION, BY MOL. PERCENT:

United States Patent ce 3,759,832 FERRITE MATERIAL Boris Nikolaevich Ermakov, ulitsa Leni Golikova 10, kv. 39, and Viktor Georgievich Kurilenko, nab. r. Fontanki 18, kv. 6, both of Leningrad, U.S.S.R.

No Drawing. Continuation-impart of abandoned application Ser. No. 748,907, July 31, 1968. This application July 16, 1971, Ser. No. 163,478

Int. Cl. C04b 35/28 US. Cl. 252-62.63 3 Claims ABSTRACT OF THE DISCLOSURE Ferrite materials having for their basic components ferric oxide and nickel oxide. The ferrite material (ferrite) also includes cobalt oxide and lead oxide, which makes it possible to extend the operational frequency range of the material up to 400M c.p.s. The ferrite has the following composition, by mol. percent:

Ferric oxide 38-48 Lead oxide 0.5-3.0 Cobalt oxide 0.7-2.0 Nickel oxide 50.0-60.8

Articles are made from the herein disclosed nickel ferrite including cobalt oxide and lead oxide additives in accordance with the known ceramic industry technology.

CROSS RELATED APPLICATIONS This application is a continuation-in-part of the application Ser. No. 748,907 filed July 31, 1968, and now abandoned.

BACKGROUND (a) Field of the invention (1) The present invention relates to materials used in radio engineering, operable within a 100 to 400M c.p.s. frequency range.

Prior art (2) There are known in the art nickel ferrites of a stoichiometric composition, containing 50% Fe O and 50% MO and having a cubic structure. These ferrites are operative at frequencies below 200M c.p.s. and have magnetic permeabilty 1. equal to to 12 G/oe. and losses ,0." equal to 6.0 where the term losses Qt") is meant to indicate the imaginary part of complex magnetic permeability (pi- =pt-'y,u")

At higher frequencies the employment of nickel ferrites is impeded by sharply increasing losses ,u" and decreasing magnetic permeability ,u.'. Nickel ferrites including cobalt oxide as an additive feature lower losses 0.3, but, on the other hand, their magnetic permeability is also lower: =l.5 to 2.0 G/oe., which makes their use less effective. Moreover, the last-mentioned ferrites exhibit a marked growth of the losses upon being remagnetized in a constant magnetic field.

Thus, ferrites having a hexagonal structure have been hitherto recommendable for use with frequencies ranging from 100 to 400M c.p.s. However, these hexagonal structure ferrites are not free from certain drawbacks, such as increased losses, particularly, with increased intensities of the high-frequency field, as well as complicated manufacture of such ferrites involving, as it does, high baking temperatures, the use of oxygen atmosphere and repeated grinding and baking.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ferrite which is capable of operation at frequencies ranging from to 400M c.p.s. under the action of two different fields applied thereto, namely, of a high-frequency field with varying amplitude and of a constant field.

The ferrite, in accordance with the present invention, should have the following characteristics at a frequency of 200M c.p.s.: magnetic permeability =3 to 7 G/oe. and losses t below 0.3.

It is a further object of the present invention to broaden the range of the operating frequencies of nickel ferrites, to reduce the losses both in weak and strong high-frequency fields without any considerable reduction of the magnetic permeability thereof and to provide the possibility of effecting cyclic remagnetization of these ferrites in a constant field, which should not be accompanied by any substantial alteration of the value of the losses and that of the magnetic permeability thereof.

The main characteristic feature of the present invention is that the broadening of the operating frequency range and the reduction of the level of losses of nickel ferrites are effected in strong and. weak high-frequency fields by the introduction thereto of a cobalt oxide additive in the amount of 0.7 to 2.0% mol.

However, this additive has been found to reduce substantially the magnetic permeability of the ferrites, down to the value of ,u.'-=2 to 3 G/oe.

It has been found that the introduction of a lead oxide additive in the quantity of 0.5 to 3.0% mol, acting as a flux, steps up the magnetic permeability and thus compensates for the adverse action of the cobalt oxide additive, without increasing the level of losses.

The ferric oxide content being thus non-stoichiometric, i.e. being from 38 to 48% mol. instead of 50% and higher, there is imparted to the material in question an ability to retain the initial level of losses on cyclic remagnetization in a constant field, this ability not being found in ferrites containing 50% mol. and more ferric oxide and a cobalt oxide additive.

A ferrite material in accordance with the present invention includes the following ingredients, in percent mol.:

Ferric oxide 38-48 Lead oxide 0.5-3.0 Cobalt oxide 0.7-2.0 Nickel oxide 50.0-60.8

However, it should be noted that in the course of the manufacture of the above, ferrite lead oxide and cobalt oxide may be replaced by various known compounds which decompose upon heating and yield lead oxide and cobalt oxide.

Nickel ferrite articles with cobalt oxide and lead oxide additives are manufactured in compliance with the conventional ceramic industry techniques. The abovementioned components are blended in the desired proportion and dry-mixed in vibratory mills. The mixture thus obtained is baked at 900 C. and then is re-ground in vibratory mills. The ground product is then compressed under a specific pressure of 2000 kg./sq. cm. in the presence of 10% by weight aqueous solution of polyvinyl alcohol as a binding agent. After subsequent drying, the articles are baked at 900 C.-980 C.

3,759,832 3 4 DETAILED DESCRIPTION treated in the manner described in connection with Example 1, except that the secondary baking temperature was 950 C. The and measurements are to be found in the table hereinbelow.

The present invention will be further described in connection with the preferred embodiments thereof, accompanied by the data obtained by measurements.

MEASUREMENT DATA TABLE Frequency 200M c.p.s. at Frequency Frequency 300M c.p.s. 1100M c.p.s. H0.2 oe. H 5 00. at H 0.2 e. at HO.2 0e.

Material n e u Gl n i M" n u" 7. 0 03 7. 0 0. 035 7. 0 0. 3 7. 0 0. 3. 0 03 3. 0 O. 03 3. 0 03 3. 0 03 6. 0 O3 5. 9 03 6. 0 03 Ferrite material w gonal structure 5 1 *9. 2 73 At 500M e.p.s. frequency.

NOTE.It has been found impossible to obtain the results of measurements with specimens made of a ferrite material of a hexagonal structure. with the intensity of the high-frequency field H-equal to 5 0e. on account of the sharp growth of the losses.

EXAMPLE 1 What we claim is:

1. A ferrite material consisting of ferric oxide, nickel Ferric, nickel, Cobalt and lead OXldeS, taken In a P oxide, cobalt oxide and lead oxide, said oxides being presportion corresponding to the following percent mol. coment in the following proportion, in mol. percent: position: Ferric oxide 38048.0

C b 11: d Fe O -46; i f ZQQ I 51353 32 Lead oxide 0.5-3.0

were mixed in a vibratory mill for one hour, and then the mixture thus obtained was baked for four hours in the A ferrite mate ial, as claimed in claim wherein ambient air atmosphere at 900 C. After subsequent cool- 6011mm of ferric Oxide is 46-0M 11101- P nickel in the product was again ground in a vibratory mill for Oxide 51.0 mol. percent; lead oxide 2.0 mol. percent and one h r, cobalt oxide 1.0 mol. percent.

Then a binding agent was added to the powdered ma- 35 3- A ferrite material, as claimed in claim 1, wherein terial obtained as a result of the above operations, wherethe content of ferric oxide is 38 mol. percent; nickel after ring-shaped articles were pressure-moulded thereoxide 58.75 mol. percent; lead oxide 2.0 mol. percent from and baked in the ambient air atmosphere at 960 C. and cobalt oxide 1.25 mol. percent.

The results of the and ,1." measurements of the articles obtained are given in the table hereinbelow. 40 References Cited UNITED STATES PATENTS EXAMPLE 2 3,450,635 6/1969 Izergina 25262.63

The mixture of Example 1 was treated in the manner 3625898 12/1971 Dnessens et 252.425 described in connection with Example 1, except that the FOREIGN PATENTS secondary baking emp t was 1,498,183 9/1967 France 25262.63

The p and 11." measurements are given in the table hereinbelow. OSCAR R. VERTIZ, Primary Examiner EXAMPLE 3 I. COOPER, Assistant Examiner A mixture of the following percent mol. composition: US. Cl. X.R.

Fe O -38; NiO-58.75; PbO-2.0; CoO-1.25 was 252-6256 

